R/E/P Community

R/E/P => Klaus Heyne's Mic Lab => Topic started by: JosephDeMaio on November 25, 2013, 12:47:17 PM

Title: Sony C38
Post by: JosephDeMaio on November 25, 2013, 12:47:17 PM

Hello all,
 I have a pair of Sony C38 mics from the 70's that need jfets. Unfortunately I can't seem to find a replacement. I believe the # of the fet is CL112B, but it's a long dead number. There does not even appear to be data sheets for it anymore.
 Any help would be greatly appreciated.
Thanks,
Joe

Title: Re: Sony C38
Post by: Jim Williams on November 25, 2013, 01:26:14 PM

Try a 2SK30A, the standard Japanese fet used in those days. Many more can also be used, you may need to adjust the source resistor value to obtain the sweet spot.

Title: Re: Sony C38
Post by: klaus on November 25, 2013, 01:28:53 PM

Or, try the current (soon obsolete again) 2N3819 from Fairchild.

Title: Re: Sony C38
Post by: JosephDeMaio on November 25, 2013, 02:54:20 PM

Thanks for the replies gents, I'll give these a try and see what happens.

Title: Re: Sony C38
Post by: klaus on November 25, 2013, 04:07:31 PM

As Jim mentioned: nothing good may happen until you properly bias the new FET!

Title: Re: Sony C38
Post by: Jim Williams on November 26, 2013, 12:39:08 PM

These are also good contenders:

2SK170

LSK170, made by Linear Systems, a quieter version at 1 nv/hz/sq

J305, used by AKG and others, a faster, lower stray capacitance rf jfet. That part has a bit more top end detail than the others mentioned.